When a photographer shakes while an image is being captured by use of a camera or the like, shake or so-called camera shake arises in a captured image. Many vibration-control techniques for absorbing camera shake, to thus prevent shaking of a captured image, have hitherto been put forward.
For instance, in a known technique, a camera is provided with detection means for detecting the vibrating state of the camera; and a portion of a plurality of optical members constituting a zoom lens is moved, in response to a signal output from the detection means, in a direction to compensate for blurring of an image attributable to vibrations, thereby making corrections to camera shake and attempting to render an image stable.
Japanese Patent Laid-Open Publication No. 2005-62228 describes a zoom lens specialized in such a vibration-control technique. The zoom lens described in the patent publication includes four lens groups having, in sequence from an object, positive refractive power, negative refractive power, positive refractive power, and positive refractive power. In this zoom lens, the third lens group includes a lens group 3a and a lens group 3b having positive refractive power. The lens group 3b is moved so as to acquire a component of a direction perpendicular to the optical axis, to thus absorb camera shake. Such a zoom lens prevents occurrence of camera shake.
Moreover, in order to miniaturize a zoom lens, use of a bending optical system which bends an optical axis to an angle of about 90° has also been proposed. For instance, Japanese Patent Laid-Open Publication No. 2006-71993 describes a zoom lens including five lens groups having, in sequence from an object, positive refractive power, negative refractive power, positive refractive power, positive refractive power, and negative refractive power. In this zoom lens, a first lens group has a reflection member for bending the optical axis to an angle of about 90°. A portion of optical members constituting a fifth lens group is moved in a direction orthogonal to the optical axis, thereby absorbing camera shake. In such a zoom lens, the optical axis is bent to an angle of about 90° by means of a reflection member, and hence the longitudinal width of the zoom lens can be reduced.
However, in the zoom lens described in the former patent publication, the four lens groups are arranged in a straight line, and hence the entire zoom lens is likely to become bulky, which in turn makes the entire camera bulky.
In the latter patent publication, the zoom lens can be made compact to a certain extent by provision of a reflection member. However, the reflection member is arranged immediately behind the lens group having negative refractive power. In this case, a reflection surface of the reflection member must be made comparatively larger. Moreover, a lens on an image-surface-side, or the like, must also be made larger. Consequently, difficulty is encountered in sufficiently miniaturizing the zoom lens and an image capturing apparatus equipped with the zoom lens.
Put another way, in the prior art, difficulty is encountered in realizing a zoom lens having a sufficiently compact vibration-control function and an image capturing apparatus equipped with the zoom lens.